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Andrew Hicks
  • Bolzano, Alto Adige, Italy
Based on the observed inverse association between hyperuricemia and... more
Based on the observed inverse association between hyperuricemia and Parkinson's disease (PD) risk, the natural antioxidant activity of uric acid has been suggested to play a protective role. SLC2A9 has been indicated as the most effective of all uric acid transporters, and SLC2A9 variants have been shown to influence circulating uric acid levels. With this study, we aimed to test the association between such SLC2A9 polymorphisms and age at onset (AAO) of PD. Variants rs733175, rs737267, rs1014290, and rs6449213 within SLC2A9 were genotyped in 664 PD individuals from three European centers. The effect of each polymorphism on AAO was estimated within each center using a linear regression model adjusted for gender and genotype at the other SNPs and assuming an additive genetic model. Results across centers were combined using inverse-variance weighted fixed-effect meta-analysis. The minor allele of rs1014290, previously shown to be associated with lower serum uric acid levels, was found to be associated with a lower AAO of PD (pooled estimate -4.56 years; 95% CI -8.13, -1.00; p=0.012). The association remained significant after adjustment for multiple comparisons and was highly consistent across centers (heterogeneity, I (2) 0%). No gender differences were observed. Our study suggests that SLC2A9 genetic variants influence age of onset of Parkinson's disease.
The messenger RNAs encoding proteins of the exocytotic machinery were measured at different times following the induction of long-term potentiation or increasing neuronal activity in the dentate gyrus of the rat in vivo. In situ... more
The messenger RNAs encoding proteins of the exocytotic machinery were measured at different times following the induction of long-term potentiation or increasing neuronal activity in the dentate gyrus of the rat in vivo. In situ hybridization revealed that from the many messenger RNAs that encode proteins involved in regulated exocytosis, only those encoding synapsin I and syntaxin 1B were specifically increased. The levels of messenger RNA encoding both synapsin I and syntaxin 1B were increased on the ipsilateral side of the dorsal dentate gyrus 2 and 5 h following the induction of long-term potentiation. Syntaxin 1B was also increased in the ventral dentate gyrus at the same time-points. On the contralateral side of the dentate gyrus there was an increase in both synapsin I and syntaxin 1B at 5 h only. All of these long-term potentiation-induced changes were prevented when the tetanus was delivered in the presence of the N-methyl-D-aspartate receptor antagonist. (D(-)-2-amino-5-phosphonopentanoic acid. Immunocytochemical staining revealed that protein levels for both synapsin I and syntaxin 1B were elevated in the mossy fibre terminal zone of CA3 5 h after the induction of long-term potentiation. In addition to these plasticity-induced changes, a transient increase in the messenger RNA encoding syntaxin 1B was observed at 2 h in conditions of high intensity stimulation of the perforant path to increase the level of cellular activation, but this change was not maintained even when high intensity stimulation was sustained for 5 h. No changes in either of the messenger RNAs were observed under low frequency stimulation and pseudotetanus at either time-points. These results show that an overall increase in neuronal excitation within a neuronal network can be differentiated from a change in synaptic strength at a specific subset of the synapses, where only synaptic plasticity leads to long-term changes in the expression of selective members of the exocytotic machinery. Altered concentrations of key vesicle proteins may thus provide the means for modulation of neurotransmitter release over long time-periods. The persistent long-term potentiation-induced postsynaptic increase in messenger RNAs encoding these presynaptic proteins has important implications for the propagation of signals downstream from the site of long-term potentiation induction in hippocampal neural networks, and highlights a candidate molecular mechanism for mediating the propagation of synaptic plasticity in such networks.
INTRODUCTION Levodopa-induced dyskinesia frequently complicates long-term Parkinson's disease. More in-depth knowledge regarding the role of genetic factors in dyskinesia development may be important to identify parkinsonian patients... more
INTRODUCTION Levodopa-induced dyskinesia frequently complicates long-term Parkinson's disease. More in-depth knowledge regarding the role of genetic factors in dyskinesia development may be important to identify parkinsonian patients who are more prone to developing dyskinesia and clarify the molecular mechanisms underlying this condition. For this reason, we systematically reviewed studies investigating genetic factors involved in dyskinesia. METHODS A systematic search of genetic factors in Parkinson's disease dyskinesia was performed using the MEDLINE (through PubMed up to June 2019) and EMBASE databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A meta-analysis was conducted using a random effect model. RESULTS The literature search retrieved 33 studies assessing genes and variants possibly associated with dyskinesia in Parkinson's disease. The studies were published between 1984 and 2019 and included a total of 27,092 subjects of different ethnicities. Overall, 37 genes were analyzed in the studies reviewed, of which 22 were possibly associated with dyskinesia. The studies reported a total of 158 variants, of which 94 were possibly related to dyskinesia. CONCLUSION The studies reviewed demonstrated inconsistent results, possibly due to differences in screening methods and in the comparison of clinical data in a large variety of genetically- and ethnically-diverse populations. The meta-analysis failed to demonstrate any association between the rs6280 in the DRD3 gene, rs1799836 in the MAO-B, rs4680 in the COMT gene, rs34637584 in the LRRK2 gene and LID susceptibility. The role of genetic factors in LID susceptibility is still unclear and further studies are required.
Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively “long” measurement time. Multichannel systems have been developed in... more
Time-Correlated Single Photon Counting (TCSPC) is a very efficient technique for measuring weak and fast optical signals, but it is mainly limited by the relatively “long” measurement time. Multichannel systems have been developed in recent years aiming to overcome this limitation by managing several detectors or TCSPC devices in parallel. Nevertheless, if we look at state-of-the-art systems, there is still a strong trade-off between the parallelism level and performance: the higher the number of channels, the poorer the performance. In 2013, we presented a complete and compact 32 × 1 TCSPC system, composed of an array of 32 single-photon avalanche diodes connected to 32 time-to-amplitude converters, which showed that it was possible to overcome the existing trade-off. In this paper, we present an evolution of the previous work that is conceived for high-throughput fluorescence lifetime imaging microscopy. This application can be addressed by the new system thanks to a centralized l...
Recall-by-genotype (RbG) research recruits participants previously involved in genetic research based on their genotype. RbG enables the further study of a particular variant of interest, but in recalling participants, it risks disclosing... more
Recall-by-genotype (RbG) research recruits participants previously involved in genetic research based on their genotype. RbG enables the further study of a particular variant of interest, but in recalling participants, it risks disclosing potentially unwanted or distressing genetic information. Any RbG strategy must therefore be done in a manner that addresses the potential ethical and social issues. As part of an RbG pilot on the penetrance of Parkinson’s disease variants, we conducted an empirical mixed-method study with 51 participants of the Cooperative Health Research in South Tyrol (CHRIS) study to understand participant views on RbG research approach. Participants were disclosed the disease under investigation but not the individual variant carrier status. Results showed that participants filtered the information received through personal experience and enacted mechanisms to address the concerns raised by invitation by resorting to personal resources and the support provided ...
Restless legs syndrome (RLS) is a common, underdiagnosed neurological condition with an age-dependent prevalence of up to 14%. Familial aggregation has been widely shown since Ekbom's first description of the disorder in... more
Restless legs syndrome (RLS) is a common, underdiagnosed neurological condition with an age-dependent prevalence of up to 14%. Familial aggregation has been widely shown since Ekbom's first description of the disorder in 1945. Five loci (12q, 14q, 9p, 2q, and 20p) have been described so far, although no positive association with any specific genes, either within these loci or additional candidates investigated, has been reported. Two recent genome-wide association studies have reported positive association with sequence variants in or around specific genes on chromosomes 6p, 2p and 15q. The molecular findings, together with the variable expressivity of the phenotype, suggest a substantial clinical and genetic heterogeneity of RLS. This article reviews the clinical characteristics, diagnosis and epidemiology with a focus on the genetics and pathogenesis of RLS.
The SNCA gene encodes the presynaptic α-synuclein (aSyn) protein, and its mutations are associated with autosomal dominant Parkinson's disease (PD). We describe the generation of an induced pluripotent stem cell (iPSC) line of a... more
The SNCA gene encodes the presynaptic α-synuclein (aSyn) protein, and its mutations are associated with autosomal dominant Parkinson's disease (PD). We describe the generation of an induced pluripotent stem cell (iPSC) line of a patient carrying a pathogenic Ala53Thr missense mutation in the SNCA gene. Human dermal fibroblasts were reprogrammed using a non-integrating episomal method. The generated iPSC line (EURACi014-A; iPS-1.1) shows expression of pluripotency markers, the potential to differentiate into all three germ layers, and a stable karyotype. Hence, this line represents a valuable resource for the study and modeling of the processes directly controlled by aSyn.
Autosomal dominant mutations in the gene encoding α-synuclein (SNCA) were the first to be linked with hereditary Parkinson’s disease (PD). Duplication and triplication of SNCA has been observed in PD patients, together with mutations at... more
Autosomal dominant mutations in the gene encoding α-synuclein (SNCA) were the first to be linked with hereditary Parkinson’s disease (PD). Duplication and triplication of SNCA has been observed in PD patients, together with mutations at the N-terminal of the protein, among which A30P and A53T influence the formation of fibrils. By overexpressing human α-synuclein in the neuronal system of Drosophila, we functionally validated the ability of IP3K2, an ortholog of the GWAS identified risk gene, Inositol-trisphosphate 3-kinase B (ITPKB), to modulate α-synuclein toxicity in vivo. ITPKB mRNA and protein levels were also increased in SK-N-SH cells overexpressing wild-type α-synuclein, A53T or A30P mutants. Kinase overexpression was detected in the cytoplasmatic and in the nuclear compartments in all α-synuclein cell types. By quantifying mRNAs in the cortex of PD patients, we observed higher levels of ITPKB mRNA when SNCA was expressed more (p < 0.05), compared to controls. A positive ...
In Parkinson’s disease (PD) misfolded alpha-synuclein (aSyn) accumulates in the substantia nigra, where dopaminergic neurons are progressively lost. The mechanisms underlying aSyn pathology are still unclear, but they are hypothesized to... more
In Parkinson’s disease (PD) misfolded alpha-synuclein (aSyn) accumulates in the substantia nigra, where dopaminergic neurons are progressively lost. The mechanisms underlying aSyn pathology are still unclear, but they are hypothesized to involve the autophagy-lysosome pathway (ALP). LRRK2 mutations are a major cause of familial and sporadic PD, and LRRK2 kinase activity has been shown to be involved in pS129-aSyn inclusion modulation. We observed selective downregulation of the novel PD risk factor RIT2 in vitro and in vivo. Rit2 overexpression in G2019S-LRRK2 cells rescued ALP abnormalities and diminished aSyn inclusions. In vivo, viral mediated overexpression of Rit2 operated neuroprotection against AAV-A53T-aSyn. Furthermore, Rit2 overexpression prevented the A53T-aSyn-dependent increase of LRRK2 kinase activity in vivo. On the other hand, reduction of Rit2 levels leads to defects in the ALP, similar to those induced by the G2019S-LRRK2 mutation. Our data indicate that Rit2 is re...
Biallelic mutations in PINK1/PRKN cause recessive Parkinson’s disease. Given the established role of PINK1/Parkin in regulating mitochondrial dynamics, we explored mitochondrial DNA integrity and inflammation as disease modifiers in... more
Biallelic mutations in PINK1/PRKN cause recessive Parkinson’s disease. Given the established role of PINK1/Parkin in regulating mitochondrial dynamics, we explored mitochondrial DNA integrity and inflammation as disease modifiers in carriers of mutations in these genes. Mitochondrial DNA integrity was investigated in a large collection of biallelic (n = 84) and monoallelic (n = 170) carriers of PINK1/PRKN mutations, idiopathic Parkinson’s disease patients (n = 67) and controls (n = 90). In addition, we studied global gene expression and serum cytokine levels in a subset. Affected and unaffected PINK1/PRKN monoallelic mutation carriers can be distinguished by heteroplasmic mitochondrial DNA variant load (area under the curve = 0.83, CI 0.74–0.93). Biallelic PINK1/PRKN mutation carriers harbour more heteroplasmic mitochondrial DNA variants in blood (P = 0.0006, Z = 3.63) compared to monoallelic mutation carriers. This enrichment was confirmed in induced pluripotent stem cell-derived (...
Rheumatoid arthritis (RA) and osteoporosis (OP) are two comorbid complex inflammatory conditions with evidence of shared genetic background and causal relationships. We aimed to clarify the genetic architecture underlying RA and various... more
Rheumatoid arthritis (RA) and osteoporosis (OP) are two comorbid complex inflammatory conditions with evidence of shared genetic background and causal relationships. We aimed to clarify the genetic architecture underlying RA and various OP phenotypes while additionally considering an inflammatory component, C-reactive protein (CRP). Genome-wide association study summary statistics were acquired from the GEnetic Factors for OSteoporosis Consortium, Cohorts for Heart and Aging Research Consortium and UK Biobank. Mendelian randomization (MR) was used to detect the presence of causal relationships. Colocalization analysis was performed to determine shared genetic variants between CRP and OP phenotypes. Analysis of pleiotropy between traits owing to shared causal single nucleotide polymorphisms (SNPs) was performed using PL eiotropic A nalysis under CO mposite null hypothesis (PLACO). MR analysis was suggestive of horizontal pleiotropy between RA and OP traits. RA was a significant causa...

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